Hydraulic system providing successive application of force to shear means



March 19, 1963 w. THEOBALD HYDRAULIC SYSTEM PROVIDING SUCCESSIVEAPPLICATION OF FORCE TO SHEAR MEANS Filed Nov. 24, 1958 United StatesPatent HYDRAULIC SYSTEM PROVIDING SUCCESSIVE APPLICATION OF FORCE T0SHEAR MEAIQS Walter Theobald, Siegen, Westphalia, Germany, assignor toFirma Siernag Siegener Maschinenbau G.m.b.H.,

Dahlbruch, Westphalia, Germany Filed Nov. 24, 1958, Ser. No. 775,939 9Claims. (Cl. 83-554) The invention relates to power shears, and moreparticularly to an arrangement for actuating movement of shearing bladesin such shears.

It is a primary object of the invention to utilize to the fullestmeasure available hydraulic pump capacity in such power shears fordriving the operating piston actuating the shearing or operatingmovement of the blades.

Another object of the invention is the provision of an automaticarrangement for operatively connecting all the pumps in suchhydraulically operated power shears to the operating piston.

Yet another object is the provision of controls for such an automaticarrangement which are sensitive to the position of the blades and whichinitiate changes in the connections between the pumps and the operatingpiston in response to the position of the blades themselves.

A further object of the invention is to utilize pressure changesoccurring in the hydraulic system of the power shears due to theposition of the blades to actuate such controls.

An additional object of the invention is the provision of fullyautomatic controls for such power shears which cause the shears toperform all necessary movements without further manipulative steps ofthe operator once a work piece has been located between the blades ofthe shears and movement of the machine has been initiated.

Finally, it is an object of the invention to provide such an automaticarrangement which is relatively simple and rugged in its structure, andtherefore relatively inexpensive in first cost, reliable in itsoperation, and not requiring expensive maintenance.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

FIG. 1 is a somewhat schematic elevational view, partly in section, ofthe shearing arrangement of the invention.

Referring now to the drawing, there is shown a lower blade 1 fixedlyconnected to the operating cylinder 3 by means of connecting members 2.The upper blade 4 is actuated by the operating piston 5 which isreciprocably supported in operating cylinder 3. The lower blade 1 isfurthermore rigidly connected to a pair of positioning pistons 6reciproca'bly slidable in positioning cylinders 7.

The upper blade 4 is positioned and held in position preparatory to theshearing operation by opposite pairs of positioning pistons 8 and whichare reciprocably movable in respective cylinders 9 and 11.

Hydraulic fluid under pressure is supplied to cylinders 9 by a pumpwhich is driven by motor 16. The bydraulic fluid line connecting pump 15to cylinders 9 passes through an automatic three-position valve 14 and acheck valve 12 which is equipped with a throttling bypass 13. Pump 15may also be connected by valve 14 to cylinders ice 11 so as to actuatepositioning pistons 10. A remotely controlled two-position valve 17 isinterposed in the hydraulic line connecting valve 14- and cylinders 11.

The positioning cylinders 7 for the lower blade 1 are supplied withhydraulic fluid under pressure from a pump 15 actuated by a motor 16',the flow of the fluid being controlled by a remotely controlledtwo-position valve 18 interposed between pump 15' and cylinders 7.

Hydraulic pressure for actuating movement of operating piston 5 isgenerated by a battery of hydraulic pumps 25 to 30 which are driven byindividual motors 19 to 24 and the discharge lines of which areconnected by remote control valves 31 to 36 to a common pressuremanifold 136 which communicates with the larger one of the cylinderspaces of a differential cylinder 38 in which a dilferential pistonhaving a portion 37 of larger cross-sectiona1 area and a portion '39 ofsmaller cross-sectional area is reciprocably movable.

Oil is pumped under pressure into the cylinder space under difierentialpiston portion 37 and causes higher pressure to be exerted by smallerpiston portion 39 on water contained in the cylinder space 44 above thesmaller differential piston portion 39. The water in space 44 is thuscapable of transmitting pressure of the order of several thousand poundsper square inch, such as may be required for shearing heavy rolled metalplates, to the operating piston.

The pressure water line 40 which connects cylinder space 44 withoperating cylinder 3 is also connected through a check valve 42 with alow-pressure water tank 41. The necessary pressure for driving waterfrom tank 41 into Water line 40 when the latter is under very lowpressure may be provided by either arranging the tank 41 on a levelhigher than that of the other elements of the water circuit, or byconnecting the space above water level of the tank and enclosed by thetank walls to a source of compressed air under suitable pressure.

A normally closed valve 43 is opened by the diflerential piston 37-39 onits return stroke, either by direct mechanical engagement with a controlelement fastened to the piston for joint movement or by an interposedcontrol means including a limit switch actuated by the piston andenergizing a solenoid which in turn operates valve 43 in a Well knownmanner. Valve 43 when open con nects tank 41 below the water line withcylinders 3 and 44.

A pump 45 is connected with tank 41 to replenish any water leakage inthe pressure water system by water drawn from a storage container whenthe water in tank 41 drops below a predetermined level. A float switchor similar known device starts and stops the electric motor driving pump45.

Pumps 15, 15 and 25 to 30 draw oil from a common sump 46 and the valves14, 18 and 31 to 36 are arranged to return the outputs of the respectivepumps in the inoperative position.

The manifold 136 communicates through a remote control valve 47 withvalve 13 and also with cylinder 7, and is also connected to one of theoutlets of two-way valve 17.

The afore-described device operates as follows:

In the inoperative condition of the power shears illustrated, valves 14,18 and 31 to 36 are so positioned as Patented Mar. 19, 1963 3 to returnoil from pumps 15, 15 and 25 to 30 into the sump 46. I

Operation of the shears is initiated by shifting valve 18 into aposition connecting pump 15' to cylinders '7 whereby the lower blade 1is raised from the inoperative position to a preparatory position beforeshearing. The preparatory position is adjusted by the operator whopositions a limit switch 1a or arranges a control stop either of whichis engaged by lower blade 1 when it reaches the intended preparatoryposition. If t is P tion is defined by the position of a limit switswitch closes an electrical control circuit which opens normally closedvalve 47. If the prepa t y P i is defined by a stop arresting blade 1,the resultmg pressure increase in cylinder 7 is made to actuate a1.pressure switch which in turn closes an electric contro circuit to openvalve 47. The output P p 15 15 now substantially directed into manifold136 for actuating movement of differential piston 3739. I

Positioning of upper b a 4 In a Preparatory Position before shearing isinitiated by shifting of valve 14 whlch is preferably linked to valve 18for simultaneous operation. In order to cause descent of upper blade 4from the inoperative into the preparatory position, valve 14 directs theoutput of pump 15 through valve 17 into cylinders 11 whilesimultaneously permitting hydraulic fluid tov return from cylinders 9 tothe sump 46 at a ratev controlled by throttle bypass 13.

When upper blade 4 reaches the predetermined preparatory position, itmay either actuate a limit switch 411 or abut against the Work piece tobe sheared so as to cause pressure to build up in cylinder 11 foractuating a pressure switch of control means in the same manner in whichthe corresponding elements cooperate with the lower blade 1. Whichevercontrol device is used for determining the preparatory position of upperblade 4, valve 17 is switched as soon as upper blade 4 reaches thepredetermined preparatory position so as to direct the output of pump 15into manifold 136.

When both shearing blades have reached their respective preparatorypositions and thus have actuated respective limit switches or pressureswitches, a common control circuit including the switches of both bladesin series is energized to shift the positions of valves 31 to 36 and toconnect the outputs of pumps 25 to 30 to manifold 136 whereby thedifferential piston 37-39 causes water under pressure to be supplied tooperating cylinder 3 and the shearing operation is started.

When the blades 1 and 4 meet and shearing is completed, an additionallimit switch is actuated and all valves are returned to their initialpositions except valve 14 which is set for connecting the output of pump15 to cylinders 9 through check valve 12 so as to return upper blade 4to its inoperative position, the water contained in cylinder 3 isthereby pressed into cylinder 38 until the differential piston 3739 isreturned to its lowest position and thereby opens valve 43 whereupon anywater still present in cylinder 3 flows into tank 41.

The arrangement described above makes particularly effective use ofthevarious hydraulic pumps employed for actuating the movements of theshear blades. The pumps which supply pressure fluid for moving theblades from their inactive to their preparatory positions beforeshearing are thereafter utilized to assist in providing pressure for theoperating or shearing movement of the blades.

This is achieved by linking all the pumps of the power shears into acommon manifold under relatively low pressure and transforming theenergy of a relatively large volume of relatively low-pressure fluidinto the high pressure of a smaller body of secondary hydraulic fluid.This separation of the power generating from the power consuming part ofthe hydraulic circuit permits the use of water in the highpressurecircuit where leakage losses are most likely to occur, and to use oil inthe low-pressure circuit without causing corrosion of the Pumps andValves- The power shears of the invention are made to work fullyautomatically, once they are started, y the Intel" locking of a systemof remote-control valves and of control switches actuating the valvesand themselves controlled by the positions of the shearing blades. Theswitches are either actuated by mechanical elements connected to theblades and mechanically acting on the switches, or the pressure surgeoccurring in hydraulic cylinders driving a blade when the movement ofthe blade is stopped by an abutment is utilized to actuate a switchwhich in turn causes movement of a valve.

The automatic arrangement uses but a relatively small number of ruggedand inexpensive elements and is, therefore, rugged and inexpensiveitself. Individual switches or valves may readily be replaced for maintenance purposes.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofhydraulic power shears different from the types described above. Whilethe invention has been illustrated and described as embodied in powershears it is not intended to be limited to the details shown, as itsvarious modifications and structural changes may be made withoutdeparting in any way from the spirit of the present application.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1 In a hydraulically operated arrangement, in combination, a ram memberrfor moving said member from moving said member from said preparatoryposition into operative position; two independent hydraulic pump valvemeans movable between first and second paratory to said operatingposition thereof by the combined action of both hydraulic pump means.

2. In a shearing arrangement, in combination, a shearing blade;hydraulic positioning piston means for moving said blade from aninoperative into a preparatory position before shearing; hydraulicoperating piston means for moving said blade from said preparatoryposition into operative shearing position; limit switch means sensitiveto the position of said blade; two independent hydraulic pump means;valve means movable between first and second positions for connectingone of said pump means first to said positioning piston means for movingsaid blade from inoperative into preparatory position, and for thenconnecting said one piston means; control means actuated by said limitswitch means in said'preparatory position of said blade to move saidvalve means to said second position; and valve means for connecting theother of said hydraulic pump means to said operating piston means onlywhen said blade is pump means to said operating.

in said preparatory position thereof, so that said blade is moved fromsaid preparatory to said operating position thereof by the combinedaction of both hydraulic pump means.

3. In a shearing arrangement, in combination, a shearing blade;hydraulic positioning piston means for moving said blade from aninoperative into a preparatory position before shearing; hydraulicoperating piston means for moving said blade from said preparatoryposition into operative shearing position; two independent hydraulicpump means; pressure switch means sensitive to the hydraulic pressureacting upon said positioning piston means; abutment means in the form ofa workpiece for arresting movement of said blade in said preparatoryposition so that the hydraulic pressure acting upon said positioningpiston is increased when said blade reaches the preparatory positionthereof; valve means for connecting one of said pump means first to saidpositioning piston means for moving said blade from inoperative intopreparatory position, and then actuated by said pressure switch meansfor connecting said one pump means to said operating piston means; andvalve means for connecting the other of said hydraulic pump means tosaid operating piston means only when said blade is in said preparatoryposition thereof, so that said blade is moved from said preparatory tosaid operating position thereof by the combined action of both hydraulicpump means.

4. In a shearing arrangement, in combination, a shearing blade;hydraulic positioning piston means for moving said blade from aninoperative into a preparatory position before shearing; hydraulicoperating piston means for moving said blade from said preparatoryposition into operative shearing position; two independent hydraulicpump means; valve means movable between first and second positions forconnecting one of said pump means first to said positioning piston meansfor moving said blade from inoperative into preparatory position, andfor then connecting said one pump means to said operating piston means;control means actuated by said blade in said preparatory position tomove said valve means to said second position and valve means actuatedby said control means for connecting the other of said hydraulic pumpmeans to said operating piston means only when said blade is in saidpreparatory position thereof, so that said blade is moved from saidpreparatory to said operating position thereof by the combined action ofboth hydraulic pump means.

5. In a shearing arrangement in combination, a shearing blade; hydraulicpositioning piston means for moving said blade from an inoperative intoa preparatory position before shearing; hydraulic operating piston meansfor moving said blade from said preparatory position into oper ativeshearing position including an operating piston, and differential pistonmeans hydraulically connected with said operating piston for increasingthe fluid pressure acting on the same; two independent hydraulic pumpmeans; valve means movable between finst and second positions forconnecting one of said pump means first to said positioning piston meansfor moving said blade from inoperative into preparatory position, andfor then connecting said one pump means to said operating pistonmeans;control means actuated by said blade in said preparatory position tomove said valve means to said second position; valve means forconnecting the other of said hydraulic pump means to said operatingpiston means only when said blade is in said preparatory positionthereof, so that said blade is moved from said preparatory to saidoperating position thereof by the combined action of both hydraulic pumpmeans.

6. In a shearing arrangement, in combination, a shearing blade;hydraulic positioning piston means for moving said blade from aninoperative into a preparatory position before shearing; hydraulicoperating piston means for moving said blade from said preparatoryposition into operative shearing position including an operating piston,and diiferential piston means hydraulicaliy connected with saidoperating piston for increasing the fluid pressure acting on the same;two independent hydraulic pump means; first valve means movable betweenfirst and second positions for connecting one of said pump means firstto said positioning piston means for moving said blade from inoperativeinto preparatory position and for then connecting said one pump means tosaid operating piston means; control means actuated by said blade insaid preparatory position to move said valve means to said secondposition; second valve means actuated by said control means forconnecting the other of said hydraulic pump means to said operatingpiston means only when said blade is in said preparatory positionthereof, so that said blade is moved from said preparatory to saidoperating position thereof by the combined action of both hydraulic pumpmeans.

7. In a hydraulic system, in combination, hydraulic positioning pistonmeans for moving an object from an inoperative to a preparatoryposition; hydraulic operating means including an operating cylinder andan operating piston movable in said operating cylinder for moving theobject from said preparatory position to an operative position, aseparating cylinder and a separating piston in the same defining twochambers in said separating cylinder, one of said chambers being adaptedto contain a first operating liquid, and a conduit means connecting saidone chamber with said operating cylinder so that said operating pistonis operated by said first liquid; two independent pump means for pumpinga second liquid; valve means movable between first and second positionsfor connecting one of said pump means first to said positioning pistonmeans for moving the object from said inoperative to said preparatoryposition, and for then connecting said one pump means to the otherchamber of said separating cylinder so that said second liquid enterssaid other chamber; control means actuated from said operating piston insaid preparatory position to move said valve means to said secondposition; and another valve means for connecting the other of said pumpmeans to said other chamber of said separating cylinder only when theobject is in said preparatory position so that said second liquid enterssaid other chamber whereby said separating piston moves under thepressure of said second liquid pumped by both said pump means to presssaid first liquid into said operating cylinder so that the object ismoved from said preparatory position to said operation position.

8. In a hydraulic system, in combination, hydraulic positioning pistonmeans for moving an object from an inoperative to a preparatoryposition; hydraulic operating means including an operating cylinder andan operalting piston movable in said operating cylinder for moving theobject from said preparatory position to an operative position, aseparating differential cylinder and a separating differential piston inthe same defining two chambers in said separating cylinder, one of saidchambers having a smaller cross section than the other chamber and beingadapted to contain a first operating liquid, and a conduit meansconnecting said one chamber with said operating cylinder so that saidoperating piston is operated by the first liquid; two independent pumpmeans for pumping a second liquid; valve means movable between first andsecond positions for connecting one of said pump means first to saidpositioning piston means for moving the object from said inoperative tosaid preparatory posit-ion, and for then connecting said one pump meansto said other chamber of said separating cylinder so that said secondliquid enters said other chamber; control means actuated from saidoperating piston in said preparatory position .to move said valve meansto said second position; and another valve means for connecting theother of said pump means to said other chamber of said separatingcylinder only when the object is in said preparatory position so thatsaid second liquid enters said other chamber whereby said separatingpiston moves under the pressure of said second liquid pumped by bothsaid pump means to press said first liquid into said operating cylinderso that the object is moved from said preparatory position to saidoperating position.

9. In a hydraulic system, in combination, hydraulic positioning pistonmeans 'for moving an object from an inoperative to a preparatoryposition; hydraulic operating means including an operating cylinder andan operating piston for moving the object from said preparatory positionto an operative position; two independent pump means; valve meansmovable between first and second positions for connecting one of saidpump means first to said positioning piston means for moving the objectfrom said inoperative to said preparatory position, and for thenconnecting said one pump means to said operating cylinder; control meansactuated from said operating piston in said preparatory position to movesaid valve means to said second position and another valve preparatoryposition so that the object is moved from;

said preparatory position to said operating position by the combinedaction of both said pump means.

References Cited in the file of this patent UNITED STATES PATENTS786,236 Ross Mar. 28, 1905 2,058,377 Francis Oct. 20, 1936 2,403,912Doll July 16, 1946 2,573,993 Sedgwick Nov. '6, 1951 2,649,154 AdrianAug. 18, 1953 2,699,649 Messic'k Jan. 18, 1955 2,811,838 Lindsey Nov. 5,1957 2,825,405 Maass Mar. 4, 1958 2,839,895 Hemeon June 24, 19582,877,624 Zoller Mar. 17, 1959 FOREIGN PATENTS 265,252 Germany Oct. 4,1913

1. IN A HYDRAULICALLY OPERATED ARRANGEMENT, IN COMBINATION, A RAMMEMBER; HYDRAULIC POSITIONING PISTON MEANS FOR MOVING SAID MEMBER FROMAN INOPERATIVE INTO A PREPARATORY POSITION; HYDRAULIC OPERATING PISTONMEANS FOR MOVING SAID MEMBER FROM SAID PREPARATORY POSITION INTOOPERATIVE POSITION; TWO INDEPENDENT HYDRAULIC PUMP MEANS; VALVE MEANSMOVABLE BETWEEN FIRST AND SECOND POSITIONS FOR CONNECTING ONE OF SAIDPUMP MEANS FIRST TO SAID POSITIONING PISTON MEANS FOR MOVING SAID MEMBERFROM INOPERATIVE INTO PREPARATORY POSITION, AND FOR THEN CONNECTING SAIDONE PUMP MEANS TO SAID OPERATING PISTON MEANS; CONTROL MEANS ACTUATED BYSAID MEMBER IN SAID PREPARATORY POSITION TO MOVE SAID VALVE MEANS TOSAID SECOND POSITION; AND VALVE MEANS FOR CONNECTING THE OTHER OF SAIDHYDRAULIC PUMP MEANS TO SAID OPERATING PISTON MEANS ONLY WHEN SAIDMEMBER IS IN SAID PREPARATORY POSITION THEREOF, SO THAT SAID MEMBER ISMOVED FROM SAID PREPARATORY TO SAID OPERATING POSITION THEREOF BY THECOMBINED ACTION OF BOTH HYDRAULIC PUMP MEANS.